my watch does not stay charged all day

Hi,

Make sure your Apple Watch software is up to date > https://support.apple.com/en-gb/HT204641

M1 Mac mini, macOS 11.4; Watch, series 5 GPS/cellular, watchOS 7.5; iPad Pro 2nd Gen, iPadOS 14.6; iPad Air 2, iPadOS 14.6; iPhone 12 Pro, iOS 14.6; TV 4th Gen, tvOS 14.6  HomePods, audioOS 14.6 and Airport Express w/ Airplay 2